Method of tristable selective light detection with pin diode

Abstract

A method of wavelength selective detection of light is achieved using p-i-n type diode and an external resistor connected in series to the diode and applying a reverse bias voltage to said p-i-n type diode through the external resistor. Two bistable wavelength ranges are obtained in the photocurrent spectrum, and the wavelength selective light detection is achieved with an asymmetric coupled quantum well structure. A p-i-n type optical element having multiply stable responses includes a coupled quantum well structure i layer producing the anti-crossing phenomenon in response to varying electric fields. The structure includes relatively thick and relatively thin quantum well layers separated by and coupled through a relatively thin barrier layer.

I claim: 
     
       1. A method of selective light detection comprising: providing a p-i-n diode having p-type, intrinsic, and n-type layers including an asymmetrical coupled quantum well structure as the intrinsic layer, said asymmetrical coupled quantum well structure including first and second quantum well layers having a first energy band gap and different thicknesses separated by and quantum mechanically coupled through a barrier layer having a second energy band gap larger than the first energy band gap;   connecting an external resistor and a voltage power supply in series with said p-i-n diode to apply a reverse bias voltage to said p-i-n diode; and   selecting at least one of the resistance of the external resistor and the voltage of the voltage power supply to produce three stable photocurrents for light incident on the p-i-n diode.   
     
     
       2. A method of selective light detection comprising: providing a p-i-n diode having p-type, intrinsic, and n-type layers including an asymmetrical coupled quantum well structure as the intrinsic layer, said asymmetrical coupled quantum well structure including first and second quantum well layers having a first energy band gap and different thicknesses separated by and quantum mechanically coupled through a barrier layer having a second energy band gap larger than the first energy band gap;   connecting an external resistor and a voltage power supply in series with said p-i-n diode to apply a reverse bias voltage to said p-i-n diode; and   selecting at least one of the resistance of the external resistor and the voltage of the voltage power supply to produce three stable photocurrents at each power of light incident on the p-i-n diode within a range of powers of the incident light.   
     
     
       3. A method of selective light detection comprising: providing a p-i-n diode having p-type, intrinsic, and n-type layers including an asymmetrical coupled quantum well structure as the intrinsic layer, said asymmetrical coupled quantum well structure including first and second quantum well layers having a first energy band gap and different thicknesses separated by and quantum mechanically coupled through a barrier layer having a second energy band gap larger than the first energy band gap;   connecting an external resistor and a voltage power supply in series with said p-i-n diode to apply a reverse bias voltage to said p-i-n diode; and   selecting at least one of the resistance of the external resistor and the voltage of the voltage power supply to produce three stable photocurrents at each wavelength of light incident on the p-i-n diode within a range of wavelengths of the incident light.